instrucfions): The goal of the proposed research is to develop methods for loading charged calcium channel blockers into sensory neurons by entry through large-pore TRP channels. Because many TRP channels are selectively expressed in pain-sensing neurons (nociceptors), calcium channel blockers that are membrane- impermeant and inactive from the outside of cells but active from the inside can be targeted to pain-sensing neurons without affecting other types of neurons. Two major functions of calcium channels in nociceptors can be targeted by this strategy: 1) Block of transmitter release from presynaptic terminals in the spinal cord, and 2) Blocking of peripheral release of neuropeptides such as CGRP and substance P involved in inflammatory pain. Charged calcium channel blockers that block N-type calcium channels from the inside but not the outside of cells will be co-applied with agonists of TRPVl, TRPV3, TRPAl, and P2X channels to target the blockers to central and peripheral terminals of primary nociceptors. Targeting of calcium channel blockers to nociceptors should be very useful as both an investigational tool and as a therapy. As a tool, it will allow highly selective silencing of synaptic transmission from specific populations of nociceptors. Making use ofthe information and tools that will be developed In the Clapham, Ma, and Woolf projects, we can use specific agonists for various large-pore channels to target calcium channel blockers to specific subsets of neurons expressing TRPVl, TRPV3, TRPAl, and P2X channels. Doing so will allow selective block of specific modalities of pain and itch. As a therapy, the strategy should allow block of pain signaling from primary noiceptors into the spinal cord without impairing non-pain circuits in the spinal cord. Applying the strategy to block release of inflammatory neuropeptides such as substance P and CGRP from peripheral C-fiber terminals should provide a way of reducing inflammatory pain in in skin and other tissue. RELEV/VNCE (See instructions): The goal of the research in the overall Program Project is to develop new clinical treatments for pain and itch. The goal ofthe research in this project is to identify combinations of charged calcium channel blockers and TRP agonists suitable for subsequent in vivo behavioral experiments in rats and ultimately in humans.